Semiconductor device and method of manufacturing the same

ABSTRACT

A semiconductor device comprises an inorganic film on a semiconductor substrate, an intermediate film on the inorganic film and containing silicon, and an organic film on the intermediate film and containing fluorine. The organic film is made of a fluorinated arylene film. The fluorinated arylene film is made of a poly(tetrafluoro-p-xylylene), or a derivative thereof, having recurring units of formula (1)  
                 
 
     wherein X is hydrogen or fluorine. The inorganic film is made of a material that is selected from the group consisting of SiO 2 , SiN, SiC, SiOC, SiCN and SiON.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to semiconductor devices andmethods for manufacturing a semiconductor device, and more particularly,to a semiconductor device having an insulating film with a lowdielectric constant and a method for manufacturing such a semiconductordevice.

[0003] 2. Background Art

[0004] In recent years, an increase of speed of a semiconductor deviceis so remarkable that a problem on the delay of transmission has beenpresented owing to the lowering of a signal propagation speed ascribedto the parasitic capacitance between a wiring resistor and wiring or awiring layer in a multi-layered wiring structure. Such a problem tendsto become more pronounced for the reason that as the wiring width andspace are made finer as a result of the high degree of integration of asemiconductor device, the wiring resistance rises-with an increasingparasitic capacitance.

[0005] In order to prevent the signal delay based on such increasedwiring resistance and parasitic capacitance, attempts have been hithertomade to use a copper wire in place of aluminum wiring and also to use aninsulating film material of low dielectric constant as a layerinsulating film. For instance, organic insulating materials are knownincluding a SiOC (silicon oxide carbide, i.e. carbon doped siliconoxide) wherein a methyl group is introduced into SiO₂ (silicon oxide)and a polyaryl ether derivative film. However, these films have adielectric constant of about 2.6-2.9. There is now a demand of furtherlowering a dielectric constant for a semiconductor device of thegeneration where the scale-down of a design rule is more advanced.

[0006] On the other hand, SiO₂ (silicon oxide) is formed as a porousfilm is known as an insulating film of a dielectric constant that is aslow as about 2.0-2.4. Such a porous film is significantly lowered inmechanical strength, with the attendant problem that the insulating filmsuffers cracking in the course of the manufacture. Moreover, the gasesor chemicals used or generated during the manufacture are absorbed inthe pores of the porous film, thus presenting a problem of lowering filmcharacteristics and a problem wherein an after treatment becomesnecessary so as to prevent the lowering of such characteristics.

[0007] A fluorinated arylene film has been proposed as another type ofinsulating film material that satisfies a low dielectric constant ofabout 2.0-2.4 without resorting to the porosity of the film. However,since the fluorinated arylene film contains fluorine (F), it has pooradhesion to inorganic films such as a SiO₂ (silicon oxide) film, a SiN(silicon nitride) film, and a SiC (silicon carbide) film, with theproblem that a failure occurs in the separation of the films.

SUMMARY OF THE INVENTION

[0008] The invention has been accomplished in view of such problems asset out hereinabove. More particularly, an object of the invention is toprovide a semiconductor device using an organic insulating film materialwhich is able to realize a low electric constant and a method formanufacturing such a semiconductor device.

[0009] Another object of the invention is to provide a semiconductordevice wherein any failure such as of film separation does not occur inthe course of its manufacture and also a method for manufacturing such asemiconductor device.

[0010] Further objects and advantages of the invention will becomeapparent from the following description.

[0011] According to one aspect of the present invention, a semiconductordevice comprises an inorganic film on a semiconductor substrate, anintermediate film on the inorganic film and containing silicon, and anorganic film on the intermediate film and containing fluorine.

[0012] According to another aspect of the present invention, asemiconductor device having a multilayer wiring structure, comprises afirst insulating film on a lower wiring layer, an intermediate film onthe first insulating film and containing silicon, and a secondinsulating film on the intermediate. The second insulating film is ainterlayer insulating film with a low dielectric constant containingfluorine.

[0013] According to another aspect of the present invention, in a methodof manufacturing a semiconductor device, an inorganic is formed film ona semiconductor substrate. The inorganic film is subjected to plasmatreatment. An organic film containing fluorine is formed on theplasma-treated inorganic film.

[0014] According to other aspect of the present invention, in a methodof manufacturing a semiconductor device, an inorganic film is formed ona semiconductor substrate. An intermediate film containing silicon isformed on the inorganic film. An organic film containing fluorine isformed on the intermediate film.

[0015] Other and further objects, features and advantages of theinvention will appear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1A shows a method of forming a thin film according to thefirst embodiment.

[0017]FIG. 1B shows a method of forming a thin film according to thefirst embodiment.

[0018]FIG. 1C shows a method of forming a thin film according to thefirst embodiment.

[0019]FIG. 2 shows an apparatus for forming a thin film.

[0020]FIG. 3A shows a method of forming a thin film according to thesecond or third embodiment.

[0021]FIG. 3B shows a method of forming a thin film according to thesecond or third embodiment.

[0022]FIG. 3C shows a method of forming a thin film according to thesecond or third embodiment.

[0023]FIG. 4 shows a relationship between temperature and dielectricconstant.

[0024]FIG. 5 shows a semiconductor device having a multilayer wiringstructure.

[0025]FIG. 6 shows a semiconductor device having a multilayer wiringstructure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The embodiments of the present invention will be described inmore detail with reference to the accompanying drawings.

[0027] First Embodiment

[0028] Referring now to FIGS. 1A, 1B, 1C and 2, a first embodiment willbe illustrated. FIGS. 1A to 1C are schematic views showing a method forforming a thin film according to the embodiment. FIG. 2 is a blockdiagram of a thin film-forming apparatus of this embodiment. Thisembodiment is characterized in that an organic insulating film of lowdielectric constant is formed after the surface treatment of aninorganic film with plasma.

[0029] Initially, as shown in FIG. 1A, a substrate is provided whereinan inorganic film 102 with a given thickness has been formed on asemiconductor substrate 101. The inorganic film may be used materialhaving a large etching rate ratio with respect to an organic film. Theinorganic film may be used, for example, a SiO₂ film, a SiN film, a SiCfilm, a SiOC film, a SiCN film, a SiON film and the like and can beformed, for example, by a plasma CVD (chemical vapor deposition)technique.

[0030] It will be noted that the semiconductor substrate is, forexample, one where a gate electrode is formed on a silicon substrate.The silicon substrate may have an element isolation region and adiffusion layer converted to a source or drain.

[0031] Next, the substrate wherein an inorganic film has been formed onthe semiconductor substrate is set in a film-forming chamber 207 of thethin film-forming apparatus 201 of FIG. 2.

[0032] In the thin film-forming apparatus 201 of FIG. 2, a gas forplasma treatment is placed in an accommodation vessel 202. The gas forplasma treatment used in this embodiment preferably includes rare gasessuch as He, Ne and Ar, N₂, H₂ and the like, of which He is mostpreferred.

[0033] The gas for plasma treatment is passed to a pipe 203 and its flowrate is controlled at a given level by a flow rate control means 204,followed by passing through a pipe 205 toward a pipe 206. Thereafter,the gas is introduced into the film-forming chamber 207 from the pipe206. The film-forming chamber 207 is evacuated to a given level ofvacuum in the inside thereof. The substrate on which the inorganic filmhas been formed is placed in the film-forming chamber 207 while keepingat a given temperature.

[0034] Next, electrodes (not shown) disposed within the film-formingchamber 207 are applied with a radio frequency (RF) so that the surfaceof the inorganic film is subjected to plasma treatment.

[0035] For instance, as shown in FIG. 1B, a surface of the inorganicfilm 102 is treated with plasma by use of a He gas. More specifically, aHe gas is fed at a flow rate of 100 sccm and a pressure of 1 Torr.,against the substrate wherein a SiC film has been formed on a siliconsubstrate with a size of 8 inches, followed by application of a radiofrequency of 13.56 MHz at 200 W. The plasma treatment time may be, forexample, at about 60 seconds. The substrate can be kept, for example, ata temperature suited for the film formation of an organic film in asubsequent step.

[0036] The gas generated through the plasma treatment and an excess gasfor plasma treatment are discharged to outside of the thin film-formingapparatus 201 through a pressure control device 208 by means of anexhaust device 209.

[0037] The plasma treatment of the inorganic film on the surface thereofin this way allows the surface layer alone of the inorganic film to beimproved within a short time. When an organic film of low dielectricconstant is subsequently formed on the inorganic film, it becomespossible to realize good adhesion between the inorganic film and theorganic film.

[0038] Next, as shown in FIG. 1C, an organic film 103 of low dielectricconstant is formed on the inorganic film 102. In this embodiment, it ispreferred to rapidly form the organic film subsequently to the plasmatreatment. When using the thin film-forming apparatus of FIG. 2, theorganic film can be continuously formed within the same film-formingchamber while keeping the vacuum after the plasma treatment.

[0039] In the thin film-forming apparatus 201, a starting gas for a lowdielectric constant organic film is placed in the accommodation vessel210. For the organic film, a fluorinated arylene film may be used, forexample. In this case, the starting gas used is a compound of thefollowing formula including, for example, di-α, α′, α″,α′″-(tetrafluoro-p-xylylene) of the formula (4), its derivative of theformula (5), or dibromotetrafluoro-p-xylylene of the formula (6) or itsderivative of the formula (7).

[0040] The starting gas within the accommodation vessel 210 is passedfrom a pipe 211 through a flow rate control means 212 to a pipe 213,followed by feeding to a heating means 214. The flow rate control means212 controls the flow rate of the starting gas fed to the heating means214 at a given level. In the heating means 214, the starting gas isthermally decomposed at a temperature of 500° C. to 650° C., preferably550° C. to 600° C., thereby forming a gaseous polymer precursor.

[0041] For instance, where the di-α, α′, α″,α′″-(tetrafluoro-p-xylylene) compound of the formula (4), its derivativeof the formula (5), or dibromotetrafluoro-p-xylylene of the formula (6)or its derivative of the formula (7) is used as the starting material,there is produced a (tetrafluoro-p-xylylene) polymer precursor gas or aprecursor gas of a (tetrafluoro-p-xylylene) polymer derivative.

[0042] The polymer precursor gas produced in the heating means 214 istransmitted to the film-forming chamber 207 via the pipes 215 and 206.

[0043] The substrate obtained after completion of the plasma treatmentis disposed within the film-forming chamber 207. This substrate is keptat a surface temperature of −50° C. to 0° C., preferably −40° C. to −30°C. and the polymer precursor gas is passed over the inorganic film. Atthis stage, the flow rate of the polymer precursor gas is set, forexample, at 5 sccm and the film-forming pressure is set, for example, at20 mTorr. Thereafter, the-polymer precursor gas is condensed andpolymerized to form a fluorinated arylene film for use as an organicfilm of low dielectric constant on the inorganic film. It will be notedthat an excess polymer precursor gas is discharged through the pressurecontrol device 208 to the outside of the thin film-forming apparatus 201by means of an exhaust device 209.

[0044] When the di-α, α′, α″, α″′-(tetrafluoro-p-xylylene) compound ofthe formula (4) or dibromotetrafluoro-p-xylylene of the formula (6) isused as the starting material for a fluorinated arylene film, a thinfilm of poly(tetrafluoro-p-xylylene having recurring units representedby the formula 8 is formed. Where the compound represented by theformula 5 or 7 is used as the starting material, a thin film of apoly(tetrafluoro-p-xylylene) derivative having recurring unitsrepresented by the formula 9 is formed. It is to be noted that thethickness of the formed fluorinated arylene film can be controlled bycontrolling the film-forming time in the film-forming chamber. Thethickness of the fluorinated arylene film can be set, for example, atabout 200 nm to 1.5 μm.

[0045] In the practice of the invention, it is preferred to carry outthermal treatment after the formation of the fluorinated arylene film.Although the polymer deposited on the semiconductor substrate has onlyweak crystallinity prior to the thermal treatment, crystallizationproceeds when the thermal treatment is carried out at a temperature ofnot lower than 350° C. and can further proceed when the thermaltreatment is effected at 400° C. Accordingly, the thermal treatingconditions include a temperature of about 300° C. to about 500° C.,preferably about 350° C. to about 400° C., and a time of 30 minutes to180 minutes, preferably 60 minutes to 90 minutes. When the temperatureis lower than 300° C., satisfactory mechanical strength is not ensured.On the other hand, when the temperature is higher than 500° C. thedecomposition reaction of the polymer forming the deposited film takesplace.

[0046]FIG. 4 shows an example of the relationship between thermaltreatment temperature and the dielectric constant of a fluorinatedarylene film. Table 1 shows an example of the relationship betweenthermal treatment temperature and the mechanical strength of afluorinated arylene film. Incidentally, a poly(tetrafluoro-p-xylylene)film of formula 8 is used as the fluorinated arylene film. It is seenfrom FIG. 4 and Table 1 that, as the heating temperature is raised, themechanical strength is great increased while the dielectric constant isslightly raised. TABLE 1 Thermal treatment temperature (° C.) 300 350400 Young's modulus (Gpa) 6.0 7.6 9.0 Hardness (Gpa) 0.31 0.35 0.37

[0047] In this embodiment, the fluorinated arylene film is used, and theinvention is not limited thereto. Fluorine-containing organic filmsother than the fluorinated arylene film may also be used. For instance,fluorinated ethylene films, fluorinated polyimide films or fluorinatedamorphous carbon films may be used.

[0048] According to the embodiment, since an organic film of lowdielectric constant is formed after the surface treatment of aninorganic film with plasma, adhesion between the inorganic film and theorganic film can be improved. Accordingly, the yield in thesemiconductor manufacturing process can be improved with improvedreliability of the resulting product.

[0049] Second Embodiment

[0050] A second embodiment will be described with reference to FIGS. 2,3A, 3B and 3C. FIGS. 3A to 3C are schematic views showing a method offorming a thin film in the embodiment. This embodiment is characterizedin that an intermediate film is formed between an inorganic film and anorganic insulating film of low dielectric constant.

[0051] Like the first embodiment, a substrate on which an inorganic film302 having a given thickness has been formed on a semiconductorsubstrate 301 is provided (FIG. 3A). For the inorganic film, there canbe used, for example, a SiO₂ film, a SiN film, a SiC film, a SiOC film,a SiCN film, a SiON film and the like, and these films can be formed,for example, by a plasma CVD technique.

[0052] It will be noted that the semiconductor substrate used may be,for example, one wherein a gate electrode has been formed on a siliconsubstrate. The silicon substrate may be formed thereon with an elementisolation region or a diffusion layer resulting in a source or drain.

[0053] Next, as shown in FIG. 3B, a silicon-containing intermediate film303 is formed on the inorganic film 302. The formation of theintermediate film on the inorganic film leads to improved adhesion withan organic film of low dielectric constant formed in a subsequent step.

[0054] The intermediate film can be formed, for example, using a silanecoupling agent. More specifically, an intermediate film compositionwherein a silane coupling agent is dissolved in an appropriate organicsolvent and is applied onto the inorganic film, for example, by spincoating. Thereafter, the organic solvent is removed from theintermediate film composition by thermal treatment. In this way, thefilm of the silane coupling agent can be formed on the inorganic film.Examples of the organic solvent include alcohols such as ethanol,ketones such as acetone, aromatic compounds such as toluene, and esterssuch as ethyl acetate. It will be noted that the intermediatecomposition may further comprise additives such as a leveling agent.

[0055] Epoxy silane coupling agents or amino silane coupling agents maybe used, for example, as the silane coupling agent. Examples of theepoxy silane coupling agent include 3-glycidoxyropyltrimethoxysilane(formula 10). Examples of the amino silane coupling agent includeN-phenyl-3-aminopropyltrimethoxysilane (formula 11) andaminopropyltrimethoxysilane (formula 12). It should be noted that thesilicon component used for the intermediate film composition is notlimited to a monomer, but may contain an oligomer or polymer of a silanecoupling agent.

(CH₃O)₃SiC₃H₆NHC₆H₅  (11)

(CH₃O)₃SiC₃H₆NH₂  (12)

(C₂H₅O)₃SiC₃H₆NH₂  (13)

[0056] For instance, a solution where aminopropyltriethoxysilane isdissolved in methanol in 10% by volume is applied onto the inorganicfilm by spin coating. Thereafter, thermal treatment is carried out at150° C. for 5 minutes to remove the organic solvent by evaporation. Inthis manner, a silicon-containing intermediate film can be formed on theinorganic film.

[0057] Alternatively, a silanol compound (formula 14) may be used toform the intermediate film. For instance, an intermediate filmcomposition containing a silanol compound and an appropriate organicsolvent is used and applied onto the inorganic film, for example, byspin coating, followed by thermal treatment to remove the organicsolvent from the intermediate film composition. This results in theformation of the silicon-containing intermediate film on the inorganicfilm. Examples of the organic solvent include alcohols such as ethanol,ketones such as acetone, aromatic compounds such as toluene, and esterssuch as ethyl acetate. The intermediate film composition may furthercontain additives such as a leveling agent.

[0058] The intermediate film formed consists of a film of analkylsiloxane polymer, an alkylsilsesquioxane polymer (e.g..methylsilsesquioxane polymer MSQ), a hydrogenated silsesequioxanepolymer (HSQ), or a hydrogenated alkylsilsesquioxane polymer (HOSP),which depends on the structure of a siloxane used.

[0059] In this embodiment, the intermediate film should preferably beuniformly applied onto the inorganic film. In addition, the intermediatefilm should-preferably have a thickness sufficient to obtain goodadhesion force between the inorganic film and the organic film.

[0060] Next, as shown in FIG. 3C, an organic film 304 of low dielectricconstant is formed on the intermediate film 303. For instance, thesubstrate is placed in the film-forming chamber 207 of the thinfilm-forming apparatus 201 of FIG. 2, and a fluorinated arylene film isformed on the intermediate film in the same manner as in the firstembodiment. Other type of fluorine-containing organic film other thanthe fluorinated arylene film may be formed. For example, a fluorinatedethylene film, a fluorinated polyimide film or a fluorinated amorphouscarbon film may be formed.

[0061] After the formation of the organic film, it is preferred to carryout thermal treatment in the same manner as in the first embodiment. Thethermal treatment can facilitate the organic film to be morecrystallized, and permits the intermediate film and the inorganic film,and the intermediate film and the organic film to be reacted,respectively, thereby more improving adhesion therebetween for bothcases. The heat treating conditions include a temperature of about 300°C. to about 500° C., preferably about 350° C. to about 400° C., and atime of 30 minutes to 180 minutes, preferably 60 minutes to 90 minutes.If the temperature is lower than 300° C., satisfactory mechanicalstrength is not ensured. On the other hand, when the temperature ishigher than 500° C., the decomposition reaction of the polymer formingthe deposited film takes place.

[0062] According to the embodiment, since the silicon-containingintermediate film is interposed between the inorganic film and theorganic film of low dielectric constant, adhesion between the inorganicfilm and the organic film can be improved. Accordingly, the yield in thesemiconductor manufacturing process can be improved with improvedreliability of the resulting product.

[0063] For example, after the completion of up to the organic filmformation process, incisions reaching the silicon substrate from theorganic film were given to a semiconductor device to form 100 smallsquares each measuring 1 mm×1 mm in a square measuring 1 cm×1 cm. Then,a tape was stuck over the incisions and thereafter unstuck from the samewith a fixed force. Thus, the adhesion between the films was evaluatedby counting the number of the small squares corresponding to part of theorganic film that was separated from the counterpart. The results areshown in Table 2. It is to be noted that the adhesion in Table 2represents (the number of small squares corresponding to part of theorganic film separated from the counterpart/100)×100 (%). TABLE 2Adhesion (%) Prior art 100 First Embodiment 4-7 Second Embodiment 0-3

[0064] Table 2 shows that the first and second embodiments are moreimproved in adhesion than the prior art.

[0065] In this embodiment, the procedure of forming a silicon-containingintermediate film by use of a silane coupling agent has been set forth,to which the invention should not be construed as limiting thereto. Forinstance, the intermediate film may be formed using a compound having astructure wherein an organic functional group is attached to silicon,e.g. a silazane or alkoxysilane.

[0066] This embodiment may be used in combination with the firstembodiment. In other words, after plasma treatment of the substrate setwithin the film-forming chamber, a silane coupling agent may be used toform an intermediate film. This permits the adhesion force between theinorganic film and the intermediate film to be improved. The plasmatreatment may be carried out by use of a gas such as He, Ne, Ar, N₂ orH₂.

[0067]FIG. 5 is a cross-sectional view of a semiconductor devicefabricated in accordance with the present embodiment, showing an examplein which a copper wiring layer 402 is formed on a lower wiring layer401. Although the structure of the lower wiring layer 401 is omitted forsimplificaton, the lower wiring layer 401 may be configured such that atungsten plug reaching a diffusion layer is formed in a siliconsubstrate.

[0068] Referring to FIG. 5, a first insulating film 403 serves as theinorganic film of this embodiment and acts as a diffusion-preventivefilm. A second insulating film 404 serves as the fluorine-containingorganic film of this embodiment and acts as an interlayer insulatingfilm of low dielectric constant (a dielectric constant of 2.0 to 2.4).An intermediate film 405 according to the embodiment is interposedbetween the first insulating film 403 and the second insulating film404. Incidentally, reference numerals 406, 407, and 408 denote a SiCfilm, a SiO₂ film and an aluminum wiring layer, respectively.

[0069] The first insulating film 403 may have a thickness of, e.g.,about 30 to 50 nm. The intermediate film 405 may have a thickness of,e.g., about 5 to 10 nm. The second insulating film 404 may have athickness of, e.g., about 150 to 200 nm.

[0070]FIG. 6 is a cross-sectional view of another example semiconductordevice according to the present embodiment. Referring to FIG. 6, a firstcopper wiring layer 502 formed on a lower wiring layer 501 iselectrically connected to a second copper wiring layer 504 through a viaplug 503. A first insulating film 505 serves as the inorganic film ofthis embodiment and acts as a diffusion-preventive film. A secondinsulating film 506 serves as the fluorine-containing organic film(second organic film) and acts as an interlayer insulating film of lowdielectric constant. An intermediate film 507 according to theembodiment is interposed between the first insulating film 505 and thesecond insulating film 506. Incidentally, reference numerals 508, 509,and 510 denote a SiC film, a SiO₂ film and an aluminum wiring layer,respectively.

[0071] The copper wiring layer in the example of FIG. 5 is formed by aDamascene method. For example, the second insulating film 404 isdry-etched to define an opening reaching the lower wiring layer 401.Thereafter the opening is filled with copper to form the copper wiringlayer 402. This copper filling is achieved by forming a copper layer byplating to fill the opening and then polishing its surface to leavecopper only in the opening by a CMP (Chemical Mechanical Polishing)method. Incidentally, the same is true of the example of FIG. 6.

[0072] According to the embodiment, the existence of the intermediatefilm 405 improves the adhesion between the second insulating film 404and the first insulating film 403. Likewise, the existence of theintermediate film 507 improves the adhesion between the secondinsulating film 506 and the first insulating film 505. Therefore, noseparation of the films occurs even if the external force due to thepolishing is exerted to the films. Thus, it is possible to manufacture asemiconductor device excellent in electric characteristics andreliability.

[0073] Incidentally, although FIG. 6 shows the two wiring layers by wayof example, the present embodiment is applicable to the example of amultilayer wiring structure having three layers or more (e.g., tenlayers).

[0074] Third Embodiment

[0075] A third embodiment will be described with reference to FIGS. 2,3A, 3B and 3C. The semiconductor device in this embodiment has such astructure as the second embodiment and is characterized in that theintermediate film is formed according to a procedure different from thatof the second embodiment.

[0076] Like the first embodiment, a substrate wherein an inorganic film302 having a given thickness has been formed on a semiconductorsubstrate 301 is provided (FIG. 3A). Examples of the inorganic filminclude a SiO₂ film, a SiN film, a SiC film, a SiOC film, a SiCN film,and a SiON film, and these films can be formed, for example, by a plasmaCVD technique.

[0077] It will be noted that the semiconductor substrate used may be,for example, one wherein a gate electrode has been formed on a siliconsubstrate. The silicon substrate may be formed thereon with an elementisolation region or a diffusion layer resulting in a source or drain.

[0078] Next, as shown in FIG. 3B, a silicon-containing intermediate film303 is formed on the inorganic film 302. In this embodiment, a vapor ofa silane coupling agent is used to form the intermediate film, forexample, by use of the thin film-forming apparatus 201 of FIG. 2.

[0079] An epoxy silane coupling agent such as, for example,3-glycidoxypropyltrimethoxysilane may be used as the silane couplingagent. Alternatively, an amino silane coupling agent such asN-Phenyl-3-aminopropyltrimethoxysilane, aminopropyltrimethoxysilane oraminopropyltriethoxysilane may also be used.

[0080] In FIG. 2, a silane coupling agent is placed in the accommodationvessel 202. After evaporation and vaporization with a heating device(not shown), the silane coupling agent is fed through a pipe 203 to aflow rate control means 204. After controlling to a given flow rate bythe flow rate control means 204, the agent is directed through a pipe205 toward a pipe 206, followed by introduction from the pipe 206 intoa-film-forming chamber 207.

[0081] The substrate formed with the inorganic film is set in thefilm-forming chamber 207. When the surface temperature of the substrateis kept low, the vapor of the silane coupling agent introduced into thefilm-forming chamber 207 is condensed to form a film. In this manner, asilicon-containing intermediate film can be formed on the inorganicfilm.

[0082] For instance, a substrate wherein a SiOC film has been formed ona silicon substrate is set within the film-forming chamber 207. Theelectrostatic chucks (not shown) for holding the substrate are kept at atemperature of about −30° C. Aminopropyltriethbxysilane is placed in theaccommodation vessel 202, and a vapor of aminopropyltriethoxysilane isintroduced into the film-forming chamber 207. The thus introduced vaporis condensed on the SiOC film to form a thin film of theaminopropyltriethoxysilane.

[0083] Subsequently, as shown in FIG. 3C, an organic film 34 of lowdielectric constant is formed on the intermediate film. Using the thinfilm-forming apparatus 201 of FIG. 2, the formation of the organic filmcan be continuously performed within the same film-forming chamber 207while keeping the vacuum after the formation of the intermediate film.

[0084] For instance, a polymer precursor gas for fluorinated arylenefilm is introduced into the film-forming chamber in the same manner asin the first embodiment to form a fluorinated arylene film on theintermediate film. Alternatively, a fluorine-containing organic filmother than the fluorinated arylene film may be formed. For example, afluorinated ethylene film, a fluorinated polyimide film or a fluorinateamorphous carbon film may be formed.

[0085] It is preferred that after the formation of the organic film,thermal treatment is carried out in the same manner as in the firstembodiment. The thermal treatment not only permits the organic film tobe further crystallized, but also causes the intermediate film and theinorganic film and also the intermediate film and the organic film to bereacted with each other, respectively, thereby improving adhesiontherebetween. The thermal treating conditions include a temperature ofabout 300° C. to about 500° C., preferably about 350° C. to about 400°C., and a time of 30 minutes to 180 minutes, preferably 60 minutes to 90minutes. If the temperature is lower than 300° C., satisfactorymechanical strength is not ensured. On the other hand, when thetemperature is higher than 500° C., the decomposition reaction of thepolymer forming the deposited film takes place.

[0086] According to this embodiment, the following effects can beobtained, aside from those effects of the second embodiment. Morespecifically, since an intermediate film and an organic film arecontinuously formed by use of the thin film-forming apparatus 1, thecontamination with foreign matter is prevented, thereby furtherimproving a yield.

[0087] It will be noted that in this embodiment, the procedure offorming the silicon-containing intermediate film with use of a silanecoupling agent has been set forth, to which the invention should not beconstrued as limiting thereto. For example, the intermediate film may beformed by using a vapor of a compound having such a structure as to havean organic functional group attached to silicon, e. g., a silazane oralkoxysilane.

[0088] This embodiment may be performed in combination with the firstembodiment. More specifically, after plasma treatment of a substrate setin the film-forming chamber, an intermediate film is formed byintroducing a vapor of a silane coupling agent thereinto. Subsequently,an organic film of low dielectric constant is formed. The plasmatreatment is carried out prior to the formation of the intermediatefilm, so that adhesion between the inorganic film and the intermediatefilm can be improved. The plasma treatment is effected using a gas ofHe, Ne, Ar, N₂ or H₂.

[0089] The intermediate film formed in the present embodiment isapplicable to the examples of FIGS. 5 and 6. That is, the respectiveintermediate films 405 and 507 of FIGS. 5 and 6 are each replaceablewith the intermediate film of this embodiment.

[0090] In the first to third embodiments, instances of forming anorganic film of low dielectric constant on an inorganic film have beenillustrated, to which the invention is not limited. Other structures mayalso be used so far as it is intended to improve adhesion between anorganic film and an inorganic film, and it is possible to apply theseembodiments to all the steps of building up thin films using an organicfilm.

[0091] The features and advantages of the present invention may besummarized as follows.

[0092] According to one aspect, an insulating film capable of realizinga low dielectric constant can be provided, so that a parasiticcapacitance of a semiconductor device can be significantly reduced, anda signal delay caused by scale-down can be minimized.

[0093] According to another aspect, failures such as film separation canbe reduced, so that a yield in the course of the manufacture of asemiconductor device can be improved. A semiconductor device ofexcellent reliability can be manufactured.

[0094] Obviously many modifications and variations of the presentinvention are possible in the light of the above teachings. It istherefore to be understood that within the scope of the appended claimsthe invention may be practiced otherwise than as specifically described.

[0095] The entire disclosure of a Japanese Patent Application No.2003-071888, filed on Mar. 17, 2003 including specification, claims,drawings and summary, on which the Convention priority of the presentapplication is based, are incorporated herein by reference in itsentirety.

What is claimed is:
 1. A semiconductor device comprising: an inorganicfilm on a semiconductor substrate; an intermediate film on saidinorganic film and containing silicon; and an organic film on saidintermediate film and containing fluorine.
 2. The semiconductor deviceaccording to claim 1, wherein said organic film is made of a fluorinatedarylene film.
 3. The semiconductor device according to claim 2, whereinsaid fluorinated arylene film is made of a poly(tetrafluoro-p-xylylene),or a derivative thereof, having recurring units of formula (1)

wherein X is hydrogen or fluorine.
 4. The semiconductor device accordingto claim 1, wherein said inorganic film is made of a material that isselected from the group consisting of SiO₂, SiN, SiC, SiOC, SiCN andSiON.
 5. A semiconductor device having a multilayer wiring structure,comprising: a first insulating film on a lower wiring layer; anintermediate film on said first insulating film and containing silicon;and a second insulating film on said intermediate; wherein said secondinsulating film is an interlayer insulating film with a low dielectricconstant containing fluorine.
 6. The semiconductor device having amultilayer wiring structure according to claim 5, wherein said secondinsulating film is made of a fluorinated arylene film.
 7. Thesemiconductor device having a multilayer wiring structure according toclaim 6, wherein said fluorinated arylene film is made of a film of apoly(tetrafluoro-p-xylylene), or a derivative thereof, having recurringunits of formula (2)

wherein X is hydrogen or fluorine.
 8. The semiconductor device having amultilayer wiring structure according to claim 5, wherein said firstinsulating film is made of a material that is selected from the groupconsisting of SiO₂, SiN, SiC, SiOC, SiCN and SiON.
 9. A method ofmanufacturing a semiconductor device, said method comprising the stepsof: forming an inorganic film on a semiconductor substrate; subjectingsaid inorganic film to plasma treatment; and forming an organic filmcontaining fluorine on the plasma treated inorganic film.
 10. The methodfor manufacturing a semiconductor device according to claim 9, whereinsaid plasma treatment is carried out using a gas selected from the groupconsisting of He, Ne, Ar, N₂ and H₂.
 11. A method of manufacturing asemiconductor device, comprising the steps of: forming an inorganic filmon a semiconductor substrate; forming an intermediate film containingsilicon on said inorganic film; and forming an organic film containingfluorine on said intermediate film.
 12. The method of manufacturing asemiconductor device according to claim 11, wherein the step of formingsaid intermediate film comprises the steps of: applying, onto saidinorganic film, an-intermediate film composition containing a silanecoupling agent and an organic solvent; and removing said organic solventfrom said intermediate film composition through thermal treatment. 13.The method of manufacturing a semiconductor device according to claim12, wherein said silane coupling agent is made of an epoxy-based silanecoupling agent or an amino-based silane coupling agent.
 14. The methodof manufacturing a semiconductor device according to claim 11, whereinthe step of forming said intermediate film comprises the steps of:directing a vapor of a silane coupling agent over said inorganic film;and condensing said vapor on said inorganic film.
 15. The method ofmanufacturing a semiconductor device according to claim 14, wherein saidsilane coupling agent is made of an epoxy-based silane coupling agent oran amino-based silane coupling agent.
 16. The method for manufacturing asemiconductor device according to claim 11, wherein the step of formingsaid intermediate film comprises the steps of: applying, onto saidinorganic film, an intermediate film composition containing a silanolcompound and an organic solvent; and removing said organic solvent fromsaid intermediate film composition through thermal treatment.
 17. Themethod for manufacturing a semiconductor device according to claim 11,wherein said intermediate film is formed after plasma treatment of saidinorganic film.
 18. The method for manufacturing a semiconductor deviceaccording to claim 17, wherein said plasma treatment is carried outusing a gas selected from the group consisting of He, Ne, Ar, N₂ and H₂.19. The method for manufacturing a semiconductor device according toclaim 9, wherein thermal treatment is carried out at a temperature of300° C. to 500° C. after the formation of said organic film.
 20. Themethod for manufacturing a semiconductor device according to claim 11,wherein thermal treatment is carried out at a temperature of 300° C. to500° C. after the formation of said organic film.